Oscillatory systems and mechanisms of the mass-spring type comprise coupling a measurable body weight to the end of a spring capable of resilient deformation, the other end of the spring being coupled to an usually fixed reference point. In these types of systems and mechanisms, the mass can be displaced from its equilibrium position (by an external force), causing deformation in the spring (in the line of its length). Once the external force is removed, the mass tends to return to its equilibrium position (due to the spring force) by executing an oscillatory motion.
From the functional point of view, one of the ends of the spring can be coupled to mass and the other end of the spring can be coupled to an external power source. Thus, the external power source begins to integrate the system/mechanism, so that the movement of the mass becomes oscillating and constant.
In resonant arrangements, it is aimed that the system/mechanism to work at maximum efficiency, where the mass oscillates at maximum amplitude from an external minimum force at certain frequencies, which are known as “resonance frequencies”.
The current state of the art provides or the application of physical concepts in the construction of linear compressors.
Some functional examples of linear compressors based on resonant oscillating mechanisms are described in the document PI 0601645-6. Such functional examples refer to compressors wherein the piston (which slides within a cylinder, effecting the compression of a working fluid) comprises the “mass”, and the linear motor (mainly composed of a fixed stator and a moving magnet) comprises the “source of strength.” With reference to the “spring” (which comprises the coupling element between the piston and the magnet of the linear motor) it may comprise a body with resilient characteristics and capable of resonant linear vibration. Described herein are different types of linear assembly of compressors based on the same oscillating resonant concept/functional principle. In any case, all the functional examples described in the document PI 0601645-6 provide embodiments in which the linear motor/piston oscillate, at a resonant manner, at the opposite ends of the spring (or of the body having the function of the spring).
A detailed construction (based on one of the functional examples described in the document PI 0601645-6) is best seen in FIG. 1 which illustrates a linear compressor (based on resonant oscillating mechanism) belonging to the current state of the art.
Thus, the compressor CP illustrated in FIG. 1 includes a linear motor ML and a piston PT (which slides within a cylinder CL), both coupled to a resonant spring MR. The magnet of the linear motor ML is coupled to one end of the ends of the resonant spring MR and the piston PT is located coupled to the opposite end of the resonant spring ML.
All the examples described in the document PI 0601645-6 (also including the example illustrated in FIG. 1) are functional and achieve the objectives to which they are proposed. However, these same examples have a ratio of length/capacity that is subject to optimization.
As is well known to those skilled in the subject, one of the factors which determines the ability of a linear compressor comprises the path of travel of the piston within the cylinder (volume useful for the compression of a working fluid). In the case of examples so far cited and illustrated (and other similar constructions and belonging to the current state of the art), the path of travel of the piston is proportional to the length of the compressor as a whole, thus optimizing the compressor capacity involves the increase in length. Thus, it is noted that the ratio of length/capacity of the linear compressors belonging to the current state of the art prevents the construction of a miniaturized compressor with great capacity of compression.
The current state of the art further comprises linear compressors whose linear motor is arranged among a resonant assembly (springs associated with each other to perform the function of a single resonant spring).
An example of such constructiveness is described in the document WO 2007/098970. In this paper, the linear compressor is also based on oscillating resonant system/mechanism.
In this construction, there is provided a drive motor unit disposed between two resonant springs, wherein only one of these resonant springs is coupled to the piston-cylinder assembly. In this case, the linear motor provides a type of piston connected to a rod which, in turn, is coupled to the piston.
Anyway, the aforementioned limitation (limitation related on the ratio of length/capacity) is also present in this constructiveness.
Based on all the context explained above, it is evident to observe the need of development of a linear compressor free of limitation imposed by its ratio of length/capacity.